GBIF have just published three new documents to explain accuracy and uncertainty, and they provide a lot of information on how to determine and record coordinates, elevation and uncertainty - whether using a GPS or GNSS receiver, a mobile phone, a digital camera, Google Maps, Google Earth, a paper map, etc. If all you have is a textual location (10km NW of San Juan) how do you find the coordinates and what is the uncertainty. Are these accuracies and uncertainties consistent across the world or not?
Is your location deep in a cave or under the ocean as part of a dive expedition? How do you determine the coordinates in those locations - should you just use the cave mouth or the dive entry point? Or should you do more. How should you record your location if you are recording in grids? If you are observing a bird - should you record the observers location or something else?
The first document: Georeferencing Best Practices covers the theoretical aspects (how to, and why) of spatially enabling information about the location of biodiversity-related phenomena, including special consideration for ecological and marine data. It also covers approaches to large-scale and collaborative georeferencing projects. It includes a very detailed glossary of terms.
The second document: Georeferencing Quick Reference Guide provides a practical how-to guide for putting the theory into practice, especially for the point-radius georeferencing method. It is a step by step guide (well illustrated) on how to find coordinates and uncertainty from textual information.